Question

Three particles, each having a charge of 10μC are placed at the corners of an equilateral triangle of side 10 cm. The electronic potential energy of the system is :
(a) : Zero
(b) : Infinite
(c) : 27 J
(d) : 100 J

Expecting a lucid explanation. ^^"
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Answer 1

Answer:

The correct option c 27J

Explanation:

Potential energy = [(k ∙ Q1Q2)/r] here

q = 10μc at corners of equilateral triangle r = 10 cm = 0.1m

.∴ Potential energy for pals of charge = [{k(q ∙ q)}/r] + [{k(q ∙ q)}/r] + [{k(q ∙ q)}/r]

= [(3k)/r]q2

= 3 × [1/(4π∈0)] × (1/0.1) × (10 × 10–6)2 = 3 × 9 × 109 × 10 × 10–10

= 27J

Answer 2

The correct option (B) 27J

$\sf{Explanation: Potential energy = [(k . Q {}^{2} Q {}^{2} )/r] }$

here q = 10μc at corners of equilateral triangle

r = 10 cm = 0.1m

∴ Potential energy for pals of charge = [{k(q ∙ q)}/r] +[{k(q ∙ q)}/r] + [{k(q ∙ q)}/r]

$\sf{➵ [(3k)/r]q {}^{2} }$

➳ 3 × [1/(4π∈0)] × (1/0.1) × (10 × 10–6)2 = 3 × 9 × 109 × 10 × 10 – 10 = 27J